Columbia Bank & Trust and the Ryland Group of Columbia, Md., last week announced a pilot mortgage program that would permit middle income families and person to buy houses costing up to 20 per cent more than they could normally afford.

Under the Flexible Loan Insurance program (FLIP), a household earning $24,000 a year could qualify for financing on a home priced at $63,942 instead of $54,067. The downpayment is 10 per cent.

With a conventional mortgage at 9 per cent, monthly payments for the more expensive house work out to $474. Under FLIP, the first year's monthly payment is $374, it rises annually to $512 in the sixth year and continues at that rate throughout the 30-year term. This, although the finance charges amount to quarter point more overall, the lower initial monthly payment makes FLIP attractive for young homebuyers.

The graduated payments are made possible by placing up to 99 per cent of the downpayment in a savings account paying 5 per cent interest, and using both interest and principal for mortgage payments.

However, FLIP mortgages will be suggested by Ryland only for those who cannot qualify for conventional financing . The point program involves $500,000 financinf for only 9 or 10 houses. Four have already been sold on the basis, Ryland vice president Kenneth Schadei said this week.

Thus far, the Federal Home Loan Bank Board has not approved FLIP mortgages, so activity is limited to state-chartered banks. As a result, there is no secondary market in FLIP mortgages. If one is created. Columbia Bank & Trust would consider making the pilot program permanent, according to vice president Frank Neybauer.